1. Field of the Invention
This invention is directed to sensors for detecting when moving parts within a system are about to violate clearance dimensions.
2. Background of the Invention
Equipment that contains rotating or other moving parts can be damaged if sufficient clearance dimensions are not maintained. Costly damage may be avoided if the equipment or system is shut down before the parts exceed a certain tolerance. Different types of proximity probes have been developed to warn system operators of parts nearing maximum dimension tolerances, thus allowing the system operator to shut the equipment down before it is damaged or creates a safety hazard. However these proximity probes have several limitations.
Axial sensors are often used to sense the position of the internal rotating parts relative to the stationary housing or casing of the machine. Axial sensors are placed axially in relation to the rotating part. It may not be possible to fit axial sensors into a given machine due to insufficient axial space. Additionally, axially positioned sensors can only sense movement in one direction. In order to sense movement in both axial directions, more than one axial sensor is required. In certain circumstances a probe positioned in a non-axial position may serve the purpose of an axial sensor, and a single probe may sense axial movement in both axial directions.
Some proximity probes sense position and output a signal proportional to the distance between two components. The signal is generated by changes in optics or some other technique. The signal can be interpreted by electronic circuitry or digital computational devices to shut down a system before it is damaged. While these type of probes may provide detailed information on the location of moving parts, they are expensive. Additionally, they are subject to electronic noise and may occasionally give a false reading. When used in compressors in refrigeration systems, the sensor portion cannot be replaced without removing the system refrigerant charge and equalizing pressures of the system and the ambient conditions.
Thus, there is a need for an improved position limit sensor, particularly in pressurized applications.
To achieve the advantages and in accordance with the purpose of the invention, as embodied and broadly described herein, the invention includes a position sensor system to detect movement of a rotating part including a probe positioned non-axially from the rotation part, a surface on the rotating part for contacting the probe when the part moves a pre-selected distance and a sensor associated with the probe wherein when the rotating part contacts the probe, and the sensor generates a control signal.
In another aspect, the advantages of the invention are achieved and the purpose thereof is served by a method of detecting the movement of a part in a system or device including positioning a probe non-axially and adjacent to but spaced from a surface of the moving part, providing a sensor in association with the probe, and generating a signal from the sensor when the probe and the moving part contact each other.
Additional objects and advantages of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. The objects and advantages of the invention will be realized and attained by means of the elements and combinations particularly pointed out in the appended claims.
It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the invention, as claimed.
The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and together with the description, serve to explain the principles of the invention.